SAN FRANCISCO — For a century and a quarter, the SS City of Chester steamship lay forgotten at the bottom of San Francisco Bay.

But on Wednesday, the National Oceanic and Atmospheric Administration announced it found the ship by accident last year in 216 feet of water about a quarter of a mile east of the Golden Gate Bridge. The fascinating discovery is already pushing researchers to correct the historical record and recognize the heroics of Chinese crewmen once blamed for sitting idly by while white passengers drowned.

“While this is not a Titanic, we shouldn’t focus our shipwreck history on only the big names,” James Delgado, NOAA’s maritime heritage director for the Office of National Marine Sanctuaries, said at a news conference at Crissy Field at the headquarters of the Gulf of Farallones sanctuary. “Every wreck, like every person, has a story, and this is something that we’ve forgotten about — the stories of the people on the ship.”

On the misty morning of Aug. 22, 1888, the 202-foot long Chester collided with the Oceanic, a steamer twice its size carrying mostly Chinese immigrants, as the smaller ship was trying to leave the harbor and head to Eureka with 106 people aboard. The Oceanic sliced through the Chester’s bow, ripping away wooden floorboards and iron walls — launching passengers into the water. Many were trapped by the onslaught of water, while others were fighting to stay afloat in the bay’s rough waters.

Because of the dense fog, the crew members of the two ships didn’t notice each other until they were separated by half a mile. The Chester tried to avoid the Oceanic, which was arriving from Asia, but swirling tides whipped it into the approaching vessel.

Crew members aboard the Oceanic scrambled to save the Chester’s passengers, reaching down to grab their outstretched hands and hoisting them up, but six minutes later the impaled steamer sank. Sixteen people died, including two children and three crew members.

It was the second-worst maritime disaster inside the San Francisco Bay. The worst was the 1901 sinking of the SS City of Rio de Janeiro, a steamer that struck a reef, leading to 123 deaths.

After the 1888 accident, local newspapers had reported that Chinese crewmen ignored the screams of drowning white passengers, said Delgado, who grew up in San Jose and was chief scientist for the 2010 mapping of the Titanic wreck.

Despite the prejudice, courts showed at the time that the crewmen had actually displayed great heroism in saving the white passengers, according to Robert Schwemmer, NOAA’s West Coast maritime heritage coordinator. In one case, he said, a crewman jumped into the frigid water to save a child. The new discovery, he said, “adds to the story being retold correctly.”

“We’ve conducted more research into testimony, court trials and crewmen interviews,” he said. “So we can rewrite history and recognize the heroes in this case.”

Two years after the collision, a salvage crew had sailed to recover what it could of the wreck but turned back after a dead body floating in the ship’s fatal gash spooked the diver performing the recovery. So for decades the location of the shipwreck remained a mystery. Last May, however, Laura Pagano, an NOAA researcher, stumbled upon it while surveying the wreck of the freighter Fernstream, which the bay swallowed in 1952.

Pagano and her crew members were on their 30-foot aluminum hull ship when Delgado gave her a call and asked if she could expand her search area to look for the Chester.

At that time Pagano had never heard of the ship or the story behind its wreck, she said, but her crew spent an extra two days running a high-tech multi-beam sonar to find it. With the sonar, Pagano and her team painted the seafloor with sound, she said, with different colors indicating different depths in the water.

After surveying the area, Pagano returned to her lab to analyze the portrait of the ocean floor. Her eyes darted to a small red dot illuminated by a ring of yellow and green among a sea of blue.

“Even to the untrained eye, this looked like a boat,” she said. “There was a bit of excitement getting to zoom into the picture. It was a very special moment.”

When she measured the length against a chart of the boat from 1888 and found a match, she and her colleagues stood up and started cheering.

“When we knew that we had found it, we became incredibly excited to have been such a big part in the maritime history of the wreck,” she said.

Stephen Haller, a historian for Golden Gate National Park, said the shipwreck offers insights into a time when San Francisco was one of the major ports in the world.

While they have no plans to pull up the ship, Haller said, the next step will be to create an exhibit at Crissy Field that will educate people about the wreck.

“The rediscovery,” he said, “means that we have a much richer story to tell to our visitors.”

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